While Prince William is allegedly attempting to grow more hair for his wedding day using a laser follicle regeneration device, his bride is faced with a more straightforward dilemma: hair up or down?

Her stylist, Richard Ward, is widely expected to go for an up-do - but rival London hairdressers are convinced that Kate's locks should be let loose. "She's got such great hair already. It's the do of the moment," says Frankie Pullen, a senior stylist for Daniel Galvin in Mayfair.

Hair down does appear the obvious choice for Kate, given that's how she invariably wears it. "If you never wear your hair up, why would you do that on your wedding day?" asks Luke Hersheson of Daniel Hersheson (danielhersheson.com). "A bride looks best when she resembles a more polished version of herself."

Loose hair certainly has its advantages, as I found at my wedding in February. Apart from the addition of a few waves, it felt normal, which was comforting given how surreal everything else was.

The style team at Toni & Guy in London envisages Kate wearing her hair loose with a low side parting, swept over one shoulder and loosely tonged. If so, it would be quite a step for such a formal occasion. One royal aide is reported to have said: "Long hair and royal women don't mix, unless they keep it pinned in a tight bun - like Princess Anne."

Kate will have clocked a number of up-dos at the society weddings she has attended. Sara Buys wore her hair pinned back when she married the Duchess of Cornwall's son Tom Parker-Bowles in 2005, while Autumn Kelly, Peter Phillips's bride, went for a soft chignon at their wedding in 2008.

But Darren Fowler, artistic director of Clipso salons, insists that Kate's simple beauty is part of her appeal, and advises against a "statement" hairstyle. "The public aren't going to love her for trying to look like Princess Anne," he says. "I think she'd look great with her hair half up and half down," - a look Laura Parker-Bowles, Camilla's daughter, perfected when she married Harry Lopes in 2006.

Hersheson has noted a move towards vintage glamour in both catwalk and bridal hair this season. "Hair that's more dishevelled and 'undone' - like Rita Hayworth and Brigitte Bardot in their day - looks chic and alluring," he says.

It'll be interesting to see if Ward incorporates extensions into Kate's hair. Hersheson, who uses hair extensions in 95 per cent of his styling work, says their advantages have yet to be discovered by brides in London. "Even if your hair is thick and glossy, they add more texture and volume to up-dos and loose hair," he says.

The hair extension company Great Lengths ( greatlengthshair.co.uk ) even offers hair diamonds to be threaded through a bride's do, from £15 a strand - which surely won't be spotted in Westminster Abbey.

Middleton might even want to consult her future spouse about her hair do. Prior to my wedding, my husband rather disparagingly said: "You're not going to wear your hair up, are you?" After that, there was no way I was walking up the aisle with a bun.

* Daniel Hersheson: danielhersheson.com . A full head of Great Lengths Hair Extensions costs from £650 and last three to five months. Great Lengths Hair